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Bi-Amping and amp input impedance

Discussion in 'AV Receivers & Amplifiers' started by wookie, Aug 12, 2003.

  1. wookie

    wookie
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    Calling all experienced Bi-Ampers.

    I have a NAD C370 and a T752.
    I want to bi-amp and use the C370 as a power amp for front LF+ & LF-'s on three way floorstanders.
    The C370 has an input impedance of 50K, the T752 has an input impedance Z of 20k.
    Now when I bi-amp I would expect to have an input impedance (as seen by main pre outs on T752) of 14.28k (50k in parallel with 20k). I see no problem with the pre amp driving 14.28K but
    Will this impedance differential cause the bass or mid-tweeter section to be out of balance?? or louder etc????
    The amplifiers both have similar voltage gains...


    Any advice would be apreciated.

    :smashin:
     
  2. alexs2

    alexs2
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    Thats an interesting one.....some preamps DO have problems with relatively low loads,and that sort of impedance may well give some preamps a bit of a headache,notably some valve preamps with high-ish output impedances.
    I would think the best thing to do is to give NAD a ring and get their views,but in practice I think you will have no real problems,other than level matching,which you would have to do in any case.
     
  3. Nic Rhodes

    Nic Rhodes
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    passive pres are in the boat as well, all you need is a half decent buffer and I am sure the NAD has this. You should see no volume differences, the tricky bit is the same input gain
     
  4. wookie

    wookie
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    Thanks...The Beekeeper

    I want to use the T752 as a pre/mid treble amp and just use the C370 for my floorstanders bass drivers as a power amp.
    (5.1 is enough for me & this way I can utilise the t752's music abilities and the c370's grunt).


    Is there anything else I should be wary of?

    The T752 has input sensitivity and impedance of 200mv/50k ohms
    The C370 has input impedance of 20K/300pF & input sensitivity ref. rated power 1.1v.


    If the gains were dissimilar would I have to use "L pad" passive attenuators??
     

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